In conventional wireless code division multiple access (WCDMA) systems, the power of the adjacent channel could be as much as 40.7 dB higher than the in-band signal power received by the base station or mobile station. This significant difference requires that conventional baseband matched filters have a large dynamic range. Conventional fixed point finite impulse response (FIR) filters typically implement truncation and clipping scheme after the correlation block. The truncation and clipping scheme truncates a fixed number of the least significant bits from the correlator outputs and clips the signal peaks at some fixed saturation level. However, to cope with the large dynamic range of the filter input, conventional fixed point FIR filters typically use more output bits than are required in order to avoid system performance degradation. This problem is unique to fixed point FIR filters, since floating point FIR filters do not require clipping and truncation circuits.
Therefore, there is a need in the art for an improved finite impulse response (FIR) filter that is capable of processing input signals having a potentially large dynamic range without requiring the use of a large number of extra filter output bits to retain system performance. In particular, there is a need in the art for an improved FIR filter having reduced complexity that is able to process input signals having large dynamic ranges wherein size of the FIR filter outputs are optimized for the in-band signal power.